The present invention relates to carbon black for a tire tread, and more particularly to carbon black which can remarkably improve the abrasion resistance of a tire tread.
Occasions to run dump trucks and off-road cars even on good roads such as general roads as well as extremely bad roads such as mountain paths and quarries have recently been increasing in step with development of various high-performance automobiles. Inversely, occasions to run common vehicles even on rough roads in mountainous areas as well as highways maintained in good conditions has been increasing in keeping with diversification of leisure time activities.
Under such circumstances, carbon black for use in tire treads is also required to be able to impart a high abrasion resistance to a tire tread under a variety of surface conditions of roads ranging from good ones to bad ones.
In general, such grades of carbon black as having a small particle size and hence a large specific surface area, such as SAF (N-110) and ISAF (N-220), are used in applications of rubbers wherein a high abrasion resistance is required.
However, these grades of carbon black are hindered in the development of structure and particularly lowered in dibutyl phthalate absorption number of compressed sample (24M4DBP) to fail to impart to a tire tread a sufficient abrasion resistance under conditions of bad roads while notably increasing the heat build-up therein.
In contrast, when the structure of carbon black is well developed, the carbon black is greatly decreased in tinting strength to fail to impart to a tire tread a sufficient abrasion resistance under conditions of good roads, though it is improved in reinforcing effect and contributes to a slightly increasing the heat build-up in tire treads and some improvement in the abrasion resistance thereof. Accordingly, development, if made, of carbon black capable of imparting to a tire tread a high abrasion resistance under every possible surface conditions of roads ranging from good ones to bad ones without incurring any increase in the heat build-up in the tire tread can well cope with the current demand ensuing from the foregoing problems of the art. In order to meet this demand, however, antinomic characteristics of a high tinting strength and a high 24M4DBP must be simultaneously established.
The inventors of the present invention previously proposed carbon black having an excellent dispersibility in rubbers and a capability of imparting a high abrasion resistance to large tire treads (see Japanese Patent Application No. 63-195850). The inventors of the present invention have made investigations with a view to further improving the abrasion resistance of tire treads containing carbon black compounded thereinto in connection with the invention of the above-mentioned prior application and, as a result, have found out carbon black endowed with both of a high tinting strength and a high 24M4DBP.